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Glossary of Filtration Terms


A/C AccumulatorCommonly referred to as the Receiver/Drier. The AC Accumulator is a metal canister that acts as a filter for the AC system. It is filled with desiccant, a moisture absorbing material. The purpose is to filter out any debris that may be moving through the AC system and to eliminate any moisture that may be present in the AC system. 

A/C Compressor: The compressor is the power unit of the air-conditioning system that puts the refrigerant under high pressure before it pumps it into the condenser, where it changes from a gas to a liquid. A fully functioning compressor is necessary for the air-conditioning system to provide peak performance. On most cars, A/C compressors are driven by an engine-accessory belt. If the belt is worn and slips, the compressor won’t operate at full strength. Compressors can also leak refrigerant, resulting in less cold air going into the interior.  Internal parts can also fail, leading to no cold air. Not all air-conditioning problems are because the system is low on refrigerant. Some are caused by issues with system parts, such as the compressor.

A/C Expansion Valve: The Expansion Valve removes pressure from the liquid refrigerant to allow expansion or change of state from a liquid to a vapor in the evaporator. The high-pressure liquid refrigerant entering the expansion valve is quite warm. The liquid refrigerant leaving the expansion valve is quite cold. The orifice within the valve does not remove heat, but only reduces pres­sure. Heat molecules contained in the liquid refrigerant are thus allowed to spread as the refrigerant moves out of the orifice. Under a greatly reduced pressure the liquid refrigerant is at its coldest as it leaves the expansion valve and enters the Evaporator.

Air Filter (Engine Air Filter):  A filter that located in the Air Filter Housing that prevents dust, dirt and other environmental contaminants from getting into the engine.

Air Filter Housing: The air filter housing protects the air filter from any damaging elements. Also, commonly referred to as an air box or air clearer housing.

Air Intake Duct: A plastic or metal tube that connects the Air Filter Housing to the Throttle Body

Cabin Air Filter: A filter that began appearing in vehicles in 2002.  It filters the air that comes into the interior through the heating, ventilation and air-conditioning system. It catches dust, pollen and other airborne material.  Some filters are located behind the glove box and are easily accessible by freeing the glove box from its fasteners.  Others are located under the dashboard and may not be easy to reach, or under the hood where fresh air enters the climate control system.

Cabin Air Temperature Sensor: Automotive air conditioning systems use sensors to monitor air temperature. The in-Car Temperature sensor (ICTS) is an NTC that monitors the air temperature of the passenger compartment. The ambient temperature sensor (ATS) monitors the air temperature outside of the vehicle

Carburetor: A device that mixes air and fuel for internal combustion engines in the proper air–fuel ratio for combustion so that the engine can run efficiently.

Oil Drain Plug: A large nut positioned at the lowest possible point on the oil pan at the bottom of the engine. Some vehicles the Drain Plug may be on the side of the oil pan.  In most cases to remove the drain plug you can use a socket and ratchet.

Engine Oil Dipstick: The Dipstick usually has a yellow handle at the top, where you can grab hold of it and its usually on the side of the engine bay area. If you have a transverse engine (front-wheel drive) your dipstick should be located near the front of the engine. The pipe it fits into is usually curved, and the metal stick bends naturally in the direction of the curve.  At the end of the Dipstick there some markings, the word “Add“ then a dash mark, a space between another dash mark.  Lastly the word “Full “.  The space between Add and Full is where you want your Oil Level to be.  Always read your Service Manual to see how to correctly read your vehicles Engine Oil Dipstick.  Some European vehicles don’t have an oil dipstick. If you can’t find one on your vehicle, check the owner’s manual for how to check your oil.

Fuel Filter:  A filter located between the fuel tank and the fuel pump, and removes impurities that prevent your car from running at optimal performance level.  Some diesels have two fuel filters, a primary located somewhere between the fuel tank and the engine. That filter cleans the fuel before it gets to the fuel transfer pump, the second filter is usually near the engine.   which gives the fuel a final cleaning before it gets to the fuel injectors.

Fuel Injectors: Electronically controlled mechanical devices that inject the right amount of fuel into the engine, which are controlled by the engine control unit, ECU. Located in the head of the engine and are threaded into the combustion chamber. Engines have several fuel injectors and they are often connected to a fuel rail that provides the numerous injectors with equal amounts of fuel.

Fuel Lines:  Usually steel or stainless-steel tubes that carry the fuel from the fuel pump to the engine.

Fuel Pump: A pump that sends fuel from the gas tank to the engine. In most modern cars, the fuel pump is usually electrically powered and located directly in or on the fuel tank.

HVAC Blower Motor Resistor: A electric component is used to regulate a vehicle’s air conditioning system, it is the part that controls the blower motor’s fan speed according to the settings which can be changed by using the knob and turning it left or right which would increase or decrease the resistance of the flowing electric current to the spinning blower motor connected to the fan.

HVAC Blower Motor: A motor responsible for pushing air through the vents of your vehicle’s heating and air conditioning systems. These can come with or without the fan that pushes the air.

HVAC Control Module: It controls and regulates all the functions of the AC system electronically. It reads data from the cabin and the outside of the vehicle and uses that information to regulate and adjust the AC system as needed to keep the cabin at the correct temperature.

HVAC Control Panel: A unit which is made up of dials and buttons used to regulate cooling and heating in your vehicle. Usually has fan speed, temperature setting and air direction flow.

HVAC Heater Blend Door Actuator (HVAC Actuator): A actuator that controls the position of the vents that control the flow of air into your vehicle’s passenger area.

HVAC:  Heating Ventilation and Air Conditioning. Its purpose in a vehicle is to clean, cool, heat, regulate, ventilate and dehumidify the air entering the cabin, depending on the inputs of the operator as well as electronic sensors.

Idle Control Valve: Also known as Idle Air Control Valve, it controls and regulates the engine idle speed, increasing and decreasing it as necessary to keep up with operating conditions. In carbureted vehicles a similar device known as an idle speed control actuator is used.

Intake Air Temperature (IAT) Sensor: A sensor measures the temperature of the air coming into the engine. The engine computer (PCM) needs this information to estimate air density so it can balance air and fuel mixture. Colder air is more dense than hot air, so cold air requires more fuel to maintain the same air/fuel ratio. The PCM changes the air/fuel ratio by changing the length (on time) of the injector pulses.

Manifold Absolute Pressure (MAP) Sensor: A sensor used to continuously monitor the amount of air flowing into the engine, so the PCM can calculate air density, adjust the amount of fuel to spray into the combustion chamber and adjust the ignition timing.

Mas Air Flow (MAF) Sensor: A sensor that measures the amount mass of air flowing into a fuel-injected engine. The electrical system heats a thin wire or resistor in the air intake tube to over 125 degrees. Air passes over the wire on its way to the engine, the air flow cools the wire. With a comprehension of how much air is flowing into your engine, the PCM can then direct fuel injectors to add more or less gasoline to the air/fuel mixture.

Oil Filler Cap: A cap fits on top of the engine as a covering for the hole into which engine oil is poured, also serves as a release valve to prevent pressure from building up under the valve cover.

Oil Filter Wrench: A tool used to remove the engine oil filter.  This tool comes in different designs, with a metal band or chain at the top.  Another type is a socket type, which fits over the end of the filter and you use a ratchet to unscrew the filter.

Oil Filter: A filter the size of a soup can, located mostly on the bottom of the engine. The Oli Filter helps remove contaminants from your car engine’s oil that can accumulate over time so they don’t cause internal damage and costly repairs.

Pickup Tube O Ring: A rubber ring that fits between the pickup tube and the transmission case.

Pickup Tube: A rubber or steel tube that connects the transmission filter to the oil pump.

Positive Crankcase Ventilation (PCV) Valve: A valve is to meter the flow of the vapor from the crankcase to the intake manifold. The PCV valve is designed to compensate for the engine ventilation needs at varying engine speeds. It is operated by manifold vacuum which increases or decreases as engine speeds change.

Positive Crankcase Ventilation: A system that was developed to remove harmful vapors from the engine and to prevent those vapors from being expelled into the atmosphere. The PCV system does this by using manifold vacuum to draw vapors from the crankcase into the intake manifold. Vapor is then carried with the fuel/air mixture into the combustion chambers where it is burned. The flow or circulation within the system is controlled by the PCV Valve. The PCV Valve is effective as both a crankcase ventilation system and as a pollution control device.

Throttle Body: Part of the air intake system that controls the amount of air flowing into the engine, in response to driver accelerator pedal input in the main. The throttle body is usually located between the air filter box and the intake manifold, and it is usually attached to, or near, the mass airflow sensor.  On older carbureted engines, the throttle body is built into the Carburetor and via mechanical means and engine vacuum, more fuel is delivered as the valve opens.

Throttle Position Sensor (TPS):  A sensor used to monitor the air intake of an engine. The sensor is usually located on the butterfly spindle/shaft so that it can directly monitor the position of the throttle.  The TPS provides the most direct signal to the fuel injection system of what power demands are being made by the engine. The TPS signal is continually measured and combined many times per second with other data such as air temperature, engine RPM, air mass flow, and how quickly the throttle position changes.

Transmission Filter: Situated above the transmission pan, catches contaminants and any excess fluid connected to a pickup tube.

Transmission Oil Pan Gasket: A gasket between the transmission filter and the transmission pan.